The following tentative theory is to a large extent influenced by Rouart's work. This psychiatrist recognizes two fundamental forms of behaviour—periodic and intermittent.

I am not amongst those who believe that a complete understanding of the manic-depressive states can be reached within the field of psychopathology. On the other hand, it is quite impossible to render intelligible the behaviour, thoughts and feelings of these patients without reviewing the changes which occur at the psychological level. Instead of baffling myself by thinking in those speciously convenient terms “functional” and “organic”, I find it more satisfying to look at the patient from the Meyerian point of view; that is to say, as an integrated series of functional levels—an extension, if you like, of Hughlings Jackson's and Sherrington's well-known conceptions of central nervous function, downwards to the more archaic autonomic level (and all that is implied by that), and upwards into the more recently evolved realm of function, of which we can at present speak only in psychological terms, because we do not know enough to speak of it in any others. The disturbance is of the functioning organism as a whole; and I believe that the clinical picture depends to a large extent upon the levels where the disturbance is greatest. Unless all human values go by the board, however, we shall always require the aid of psychopathology to enable us to reach a complete understanding. Frustration will always produce sorrow, or a state of which sorrow is an important component; and achievement will always produce elation or one of its allied states. The converse of these propositions is not necessarily true; and although there may be strong presumptive evidence for doing so in individual cases, it is not necessarily correct to assume that because a state of joy or sorrow exists, it must have been preceded by some achievement or frustration as the case may be. To me, there are two essential parts of the problem in any given case. The first—and more difficult—is, Why does the emotional swing arise? And the second is, To what extent is the psychosis intelligible by considering the emotional change in relation to the sum total of the events that go to make up the patient's life? This involves a process of empathy—what the Germans call Einfühling—and it is relatively easy for those of cyclothymic disposition to do it. The crux of the situation is therefore the emotional change; and although its origin may not always he at the psychological level—in fact in the extreme sense I suppose it never does—I am much impressed by the psychological principle implied by MacCurdy's explanation of certain manic states. He says, in effect, that they do arise from achievement, from fulfilment—if we must use analytical terms—of an unconscious wish, in respect of which there has been and still is considerable conflict; and that the manifest thought content may be in part a secondary phenomenon, and in part a fragmentary disguise of the wish. It does not matter whether the wish is conscious or not; nor, so far as emotional value goes, does it matter whether it is achieved in fact or in phantasy. A biological urge of some kind has been fulfilled, or what is psychologically very similar, is on the verge of practical fulfilment; and the natural concomitant of that fulfilment is joy or elation. It needs but little introspection and observation to be assured of the naturalness of this reaction; and the benign qualities, which we expect, are present in proportion to its purity. It may be argued that the schizophrenic also secures achievement in phantasy; why then is he not elated? Does not the answer He in this: The manic patient's thinking and behaviour are gross; they are open for all to see; he is frankly and openly erotic or obscene or aggressive, and the more acute the attack the more gross are his thoughts and behaviour. There is no disguise—or perhaps it would be more correct to say the more acute the attack, the less the disguise. Symbols are practically unnecessary for the manic patient; so is projection; he may transfer his affect, but he does not disguise it. He is in fact uninhibited to a degree. As MacCurdy says, where there is no repression, there is no need for disguise. If one likes to put it so, the material with which the manic patient has to deal is not so deeply suppressed, is more ordinary, less archaic, less perverted, less worthy of guilt, or less infantile, according to the shibboleths of one's own psychological beliefs. Needless to say these views are quite incompatible with those of Freud and Abraham, who, although they differ as to the erogenous zone concerned, are agreed that the manic is narcissistically fixated. Anything less narcissistic than a full-blooded acute mania I have never seen. The whole keynote of the manic is that he is ordinary. He is concerned with real things, the most clamant of which is his own real emotion, with which he cannot deal if, at the same time, he is to keep his thought and behaviour directed towards ordinary everyday external goals.